| 摘要 |
A refrigeration compressor comprising first (17) and second (18) centrifugal compressor stages each having an impeller (19, 21) mounted on a shaft (22), an electric motor (27) to drive the shaft, the motor including a rotor (29) connected to the shaft and the shaft being supported by oilless radial bearings (23, 24), axial locating means (26) associated with the shaft to restrict axial movement thereof, a housing (12) enclosing the motor and impellers, passageways (14, 16) in the housing to convey refrigerant to cool the motor and to convey refrigerant gas from the motor to a gas inlet (31), a gas port (44) in the housing to convey refrigerant gas from a refrigerant expansion chamber to the second compressor stage, said housing incorporating an axially extending gas inlet and a gas outlet passage, gas throttling means (34) in the inlet to control the supply of gas to a first of the impellers, control means (30) to control the gas throttling means in response to load, said control means receiving input signals from refrigeration circuit components including evaporator means, pressure transducers (20, 25) in the gas inlet and gas outlet, gas throttling means, motor power supply means and motor speed sensor means, the control means operating to adjust the motor speed and gas throttling means in accordance with system load and logic control parameters to maintain predetermined refrigerant flow through the compressor. |
